This invention relates to the use of traditional scale inhibitors as fertilizer enhancers. More particularly, this invention relates to compositions which comprise: (a) a phosphate fertilizer and (b) a scale inhibiting compound. These compositions greatly stimulate plant growth. Further, this invention relates to a method of stimulating and increasing plant growth, and corresponding yields, comprising adding the above-defined compositions to the soil in which the plants being treated grow.
As used herein, the term "scale inhibiting compound" is defined as any compound which inhibits the precipitation of scale forming salts in aqueous systems. Scale forming salts include, but are not limited to, calcium carbonate, calcium sulfate, calcium phosphate, calcium phosphonate, calcium oxalate, calcium fluoride, barium sulfate and magnesium salts.
As used herein, the term "fertilizer" is defined as a material or combination of materials which is added to soil to improve the rate of growth or health of plants, or the yield of plant fruits.
Fertilizers are added to soils to enrich or replenish chemical nutrients in the soil which are vital to plant growth. A soil may be naturally lacking in a needed chemical nutrient, or the deficiency may be due to the taking of chemicals by crops previously grown. In either case, the use of fertilizers increases productivity, as measured by ratios such as yield per acre, or yield per man hour. Additionally, the use of fertilizers enables soil to be used continuously, since artificial addition of needed components to nutrient depleted soils replaces natural replenishment of these components through fallow.
The fact that crops deplete key chemical elements from soil is well known. Generally, plants obtain all nutrients from soil, with the exception of carbon, oxygen and hydrogen. Typical soil-based nutrients essential to plant growth include, but are not limited to, nitrogen, silicon, magnesium, oxides of iron and calcium, chlorides, sulfates, magnesia, phosphates, soda and potash. Accordingly, typical fertilizers include: nitrogen fertilizers, such as sodium nitrate (NaNO.sub.3), ammonium sulfate ((NH.sub.4).sub.2 SO.sub.4), calcium nitrate ((CaNO.sub.3).sub.2), ammonium nitrate (NH.sub.4 NO.sub.3), urea (CO(NH.sub.2).sub.2), and liquid nitrogen fertilizers, including anhydrous ammonia and aqua ammonia; phosphate fertilizers, such as apatites (Ca.sub.5 (PO.sub.4).sub.3 R, wherein R is OH, CO.sub.3, Cl or F), inorganic polyphosphates, tricalcium phosphate (Ca.sub.3 (PO.sub.4).sub.2), dicalcium phosphate (CaHPO.sub.4), monocalcium phosphate (Ca(H.sub.2 PO.sub.4).sub.2, also called single super phosphate), iron phosphates, aluminum phosphates, orthophosphoric acid and nitrophosphates; potassium fertilizers, such as potassium sulfate (K.sub.2 SO.sub.4), and potassium nitrate (KNO.sub.3), potassium chloride and potash; and combinations of nitrogen, phosphate and potassium fertilizers which, according to traditional fertilizer nomenclature, are designated as percent N-percent P.sub.2 O.sub.5 - percent KO.sub.2. Thus, many combinations are possible. For example, typical products are 20-20-0, 15-15-15, 10-34-0, 13-13-13, 12-57-0, 28-28-0, and 19-19-19. Additionally, secondary nutrients may be added to fertilizer compositions as required. Secondary nutrients include, but are not limited to, boron, copper, iron, manganese, molybdenum, zinc and magnesium.
As used herein, soil refers to the surface layer of the earth in which plants grow. This definition encompasses all types of soil, including but not limited to sandy soil, clay soils, topsoils and the like.
In accordance with the instant invention, it has been found that the addition of scale inhibiting compounds to soil, in conjunction with phosphate fertilizers, greatly enhances the effectiveness of said phosphate fertilizers. This novel use of scale inhibiting compounds produces extraordinary and unexpected results in terms of plant growth; thus, benefits associated with the instant invention include, but are not limited to, higher yield per acre, higher yield per man hour, higher yield per pound of fertilizer and reduced fertilizer consumption.
The key to this invention relates to the availability of fertilizer nutrients to plants. It is estimated that a maximum of approximately 20 percent of a fertilizer added to soil becomes available to plants. For example, it is known that a major portion of phosphate fertilizers precipitate as insoluble inorganic salts such as calcium phosphate, zinc phosphate, or salts of phosphate and other ions present in the soil. These precipitated, insoluble salts are of limited value to plants. It is also known that the type of soil used and soil pH effect the availability of specific fertilizers to plants. The scale inhibitors of the instant invention, when added to fertilizers, inhibit the precipitation of insoluble inorganic salts which occurs when the fertilizer dissolves in water, from irrigation or rain, and contacts ions present in the soil. By inhibiting precipitation of these insoluble salts, more fertilizer becomes available to the plants. Additionally, other nutrients, such as zinc ions, become available to the plants.
Scale inhibitors which have efficacy as fertilizer enhancers include, but are not limited to, phosphonates, sulfonates and polymers of ethylenically unsaturated carboxylic acids, and their salts, alone or in combination.
Though it is well known in the art to use scale inhibitors to prevent the precipitation of salts in aqueous systems, the novel use, compositions and process of the instant invention are not known in the art.